Although lowland Tropics are the richest in hydrological and biodiversity resources, the effects of tropical climate variability on these resources are still too poorly documented to predict the future of densely populated regions. The Colonia structure is located in southern Brazil, close to the city of Sao Paulo (23°52'8"S, 46°42'20"W). It contains a bog deposited in a hilly circular structure of 3.6 km diameter with an outer rim elevated by up to 125 m. The structure is formed in Proterozoic crystalline rocks and 230 m of organic-rich, fine-grained sediments fill the Colonia basin. Drilling the Colonia sediments will provide a unique archive on Southem Hemisphere climate development as well as improve our knowledge about tropical rain forest evolution.